Bug #132321 for Object-Pad: Anon methods generated other methods segfault at compiletime

Fri Apr 10 08:25:48 2020 leonerd-cpan [...] leonerd.org.uk - Ticket created

Subject:

Anon methods generated other methods segfault at compiletime

A minimal test case: use Object::Pad 0.19; class GeneratedMethod; method BUILD { my $m = method { }; } -- Paul Evans

Fri Apr 10 08:33:58 2020 leonerd-cpan [...] leonerd.org.uk - Correspondence added

Initial analysis: $ gdb --args perl -Mblib rt132321.pm (gdb) run Starting program: /usr/bin/perl -Mblib rt132321.pm [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". Program received signal SIGSEGV, Segmentation fault. 0x00007ffff7fc4fa1 in parse_pre_blockend (my_perl=<optimized out>, ctx=ctx@entry=0x7fffffffd630) at lib/Object/Pad.xs:1015 1015 PADNAMELIST *slotnames = PadlistNAMES(CvPADLIST(compclassmeta->methodscope)); (gdb) bt #0 0x00007ffff7fc4fa1 in parse_pre_blockend (my_perl=<optimized out>, ctx=ctx@entry=0x7fffffffd630) at lib/Object/Pad.xs:1015 #1 0x00007ffff7fbcbe6 in parse2 (hooksA=<optimized out>, hooksB=<optimized out>, op_ptr=<optimized out>, my_perl=<optimized out>) at lib/XS/Parse/Sublike.xs:140 #2 0x00005555555ded48 in Perl_yylex (my_perl=my_perl@entry=0x5555558a92a0) at toke.c:7205 #3 0x00005555555f49eb in Perl_yyparse (my_perl=my_perl@entry=0x5555558a92a0, gramtype=gramtype@entry=258) at perly.c:340 #4 0x00005555555c55e1 in S_parse_body (xsinit=0x55555559c570 <xs_init>, env=0x0, my_perl=0x5555558a92a0) at perl.c:2531 #5 perl_parse (my_perl=<optimized out>, xsinit=0x55555559c570 <xs_init>, argc=<optimized out>, argv=<optimized out>, env=0x0) at perl.c:1822 #6 0x000055555559c3b3 in main (argc=<optimized out>, argv=<optimized out>, env=<optimized out>) at perlmain.c:126 Probably the compclassmeta->methodscope of the outer named `method BUILD` got corrupted by the inner `method` one. -- Paul Evans

Fri Apr 10 08:40:41 2020 leonerd-cpan [...] leonerd.org.uk - Correspondence added

On Fri Apr 10 08:33:58 2020, PEVANS wrote: Show quoted text

> Probably the compclassmeta->methodscope of the outer named `method > BUILD` got corrupted by the inner `method` one.

Yup. Pretty simple fix. Patch attached. -- Paul Evans

Subject:

rt132321.patch

=== modified file 'lib/Object/Pad.xs' --- old/lib/Object/Pad.xs 2020-04-03 23:14:16 +0000 +++ new/lib/Object/Pad.xs 2020-04-10 12:39:53 +0000 @@ -782,6 +782,8 @@ meta->tmpcop = (COP *)newSTATEOP(0, NULL, NULL); CopFILE_set(meta->tmpcop, __FILE__); + meta->methodscope = NULL; + /* CARGOCULT from perl/op.c:Perl_package() */ { SAVEGENERICSV(PL_curstash); @@ -955,6 +957,11 @@ AV *slots = compclassmeta->slots; U32 nslots = av_count(slots); + /* Save the methodscope for this subparse, in case of nested methods + * (RT132321) + */ + SAVESPTR(compclassmeta->methodscope); + /* While creating the new scope CV we need to ENTER a block so as not to * break any interpvars */ === modified file 't/01method.t' --- old/t/01method.t 2020-03-25 19:14:27 +0000 +++ new/t/01method.t 2020-04-10 12:39:53 +0000 @@ -39,4 +39,20 @@ 'anon method' ); } +# nested anon method (RT132321) +{ + class RT132321 { + has $_genvalue; + + method BUILD { + $_genvalue = method { 123 }; + } + + method value { $self->$_genvalue() } + } + + my $obj = RT132321->new; + is( $obj->value, 123, '$obj->value from BUILD-generated anony method' ); +} + done_testing;

Fri Apr 10 08:40:42 2020 leonerd-cpan [...] leonerd.org.uk - Status changed from 'new' to 'patched'

Thu Apr 16 08:46:02 2020 leonerd-cpan [...] leonerd.org.uk - Status changed from 'patched' to 'resolved'

Thu Apr 16 08:46:02 2020 leonerd-cpan [...] leonerd.org.uk - Fixed in 0.20 added